Preterm birth is any birth that occurs before the 37th completed week of pregnancy. Compared to other babies, preterm babies are more likely to face lifelong health problems or even to die in the first month of life, especially if they are born very preterm (less than 32 weeks gestation).

To help prevent preterm birth:

• Know the warning signs of preterm labor.
• Get regular prenatal checkups.
• Reduce stress.
• Don’t smoke, drink alcohol or use illegal drugs. Avoid secondhand smoke.
• Call your health care provider if you feel burning or pain when you urinate. You may have an infection that can increase the risk of preterm birth.

The warning signs of preterm labor are:

• Contractions (your abdomen tightens like a fist) every 10 minutes or more often
• Change in vaginal discharge (leaking fluid or bleeding from your vagina)
• Pelvic pressure—the feeling that your baby is pushing down
• Low, dull backache
• Cramps that feel like your period
• Abdominal cramps with or without diarrhea

IMPORTANT: Call your health care provider or go to the hospital right away if you think you're having preterm labor, or if you have any of the warning signs.

Your provider may tell you to:

• Come into the office or go to the hospital for a checkup.
• Stop what you're doing. Rest on your left side for one hour.
• Drink 2-3 glasses of water or juice (not coffee or soda).

If the symptoms get worse, or don’t go away after one hour, call your health care provider again or go to the hospital. If the symptoms go away, relax for the rest of the day.

If the symptoms stop but come back, call your health care provider again or go to the hospital.

You are at high risk of preterm birth if you:

• Have had a previous preterm birth
• Are pregnant with twins, triplets or more
• Have certain uterine or cervical abnormalities

If you have any of these three risk factors, it's especially important for you to know the signs and symptoms of preterm labor and what to do if they occur.

Lifestyle and environmental risks: Some studies have found that certain lifestyle and environmental factors may put a woman at greater risk of preterm labor. These factors include:

• Late or no prenatal care
• Smoking
• Drinking alcohol
• Using illegal drugs
• Exposure to the medication DES
• Domestic violence, including physical, sexual or emotional abuse
• Lack of social support
• Stress
• Long working hours with long periods of standing

Medical risks: Certain medical conditions during pregnancy may increase the likelihood that a woman will have preterm labor. These conditions include:

• Urinary tract infections, vaginal infections, sexually transmitted infections and possibly other infections
• Diabetes
• High blood pressure
• Clotting disorders (thrombophilia)
• Bleeding from the vagina
• Certain birth defects in the baby
• Being pregnant with a single fetus after in vitro fertilization (IVF)
• Being underweight before pregnancy
• Obesity
• Short time period between pregnancies (less than 6-9 months between birth and the beginning of the next pregnancy)

Researchers also have identified other risk factors. For instance, African-American women, women younger than 17 or older than 35, and poor women are at greater risk than other women. Experts do not fully understand why and how these factors increase the risk that a woman will have preterm labor or birth.

Preterm labor and birth are increasingly appreciated to arise from a complex interplay of genetic and environmental factors. The March of Dimes funds research aimed at identifying how gene-environment interactions play a role in preterm birth. Our hope is that, through research, experts will better understand how certain factors increase a woman's risk of having preterm labor or birth.

June 2005